Polyester resins typified by polyethylene terephthalate and polybutylene terephthalate are used as various electric and electronic parts, mechanical parts, automobile parts, etc., since they have excellent properties.
However, since polyester resins are inferior in impact properties, especially notched impact strength, many proposals have been proposed for improving them. Among them, methods of blending a copolymer obtained from such monomers as an α-olefin and an α,β-unsaturated acid glycidyl ester are popularly used. The molded parts obtained by these methods show good impact properties at near room temperature but have a problem that they considerably decline in impact properties, for example, in a low temperature atmosphere of about −40° C. So, means for improving the impact properties at low temperature are disclosed, and they include a method of adding a specific glycidyl group-containing olefin copolymer and an ethylene/α-olefin copolymer (U.S. Pat. No. 4,461,871, US2002/91196), a method of adding an ethylene-vinyl acetate-based copolymer (U.S. Pat. No. 5,219,941), a method of adding an impact properties ingredient having an acid anhydride group and a specific glycidyl group-containing olefin copolymer (U.S. Pat. No. 6,660,796), etc. A means in which an impact properties improving material is added to a polyester resin and polyphenylene sulfide resin for enhancing impact properties is also disclosed (JP6-23300B).
However, even if these proposed conventional methods are used, any composition having an impact strength of 500 J/m or more in a low temperature atmosphere cannot be obtained. So, it is demanded to develop a material satisfying higher low-temperature properties. Furthermore, since the compositions obtained by these prior art are not satisfactory in the chemicals resistance against acids, alkalis and organic solvents, they are limited in applicability. Improvement in this regard is also desired.
It could therefore be advantageous to obtain a polyester resin composition having more excellent flexibility and impact properties in a low-temperature atmosphere than the conventional materials and also having excellent flowability and chemicals resistance.